In the past, there have been provided power supply control devices that control power supply from external power sources to automobiles. The external power source is, for example, a commercial 100V AC power supply. The automobile includes a battery and a charging circuit for charging the battery, is capable of running on a motor that is driven by electrical power from the battery, and specifically is a plug-in hybrid vehicle or an electric vehicle. The power supply control device is used for supplying electrical power to the charging circuit.
A power supply control device of this kind includes a relay inserted in a power supply path from the external power source to a load (charging circuit), a control circuit that controls turning on/off of the relay, and a power circuit for generating power for the control circuit. The control circuit controls the relay to be turned off, according to a signal input from the outside or when an abnormality such as an electric leakage is detected, for example.
Conventionally, the control circuit and the power circuit are mounted on different printed wiring boards (see document 1 [JP 2011-135653 A]).
However, in the case where the control circuit and the power circuit are mounted on the different printed wiring boards, as described above, it is necessary to provide conductors (such as pins or electric cables) connecting the printed wiring board on which the control circuit is mounted to the printed wiring board on which the power circuit is mounted. When such conductors are provided, there is a possibility that poor or bad connection with the printed wiring boards will occur at both ends of the conductors, and thus the possibility of such poor connection occurring as a whole is relatively high.